Alternate ways to read one line of input

[teohhanhui]

[edit: This was originally a reply to this old thread. —@mbrubeck]

I'm a complete beginner who is learning through the Book. Does it make sense to rewrite (just for learning) Listing 2-1 like this?

use std::io::{self, BufRead};

fn main() {
    println!("Guess the number!");

    println!("Please input your guess.");

    let guess = io::stdin()
        .lock()
        .lines()
        .next()
        .expect("Failed to read line")
        .expect("Failed to read line");

    println!("You guessed: {}", guess);
}

[mbrubeck]

Yes, that's a reasonable equivalent to the original code from the book.

[teohhanhui]

Thanks!

At the end of chapter 2 I've got this code (equivalent of Listing 2-6):

use rand::Rng;
use std::cmp::Ordering;
use std::io::{self, BufRead};

fn main() {
    println!("Guess the number!");

    let secret_number = rand::thread_rng().gen_range(1, 101);

    loop {
        println!("Please input your guess.");

        let guess = match io::stdin().lock().lines().next() {
            Some(Ok(line)) => line,
            Some(Err(err)) => panic!("Failed to read line: {:?}", err),
            None => continue,
        };

        let guess: u32 = match guess.trim().parse() {
            Ok(num) => num,
            Err(_) => continue,
        };

        println!("You guessed: {}", guess);

        match guess.cmp(&secret_number) {
            Ordering::Less => println!("Too small!"),
            Ordering::Greater => println!("Too big!"),
            Ordering::Equal => {
                println!("You win!");
                break;
            },
        }
    }
}